1. END-USER FOCUSED VERIFICATION OF PRECIPITATION NOWCASTS DURING THE SOCHI 2014 WINTER OLYMPICS Larisa Nikitina 1, Suleiman Mostmandy 2, Pertti Nurmi (presenter) 3 1 Aviamettelecom of Roshydromet, Russian Federation, (nikfia@mail.ru) 2 North-west department of Roshydromet, Russian Federation (http://suleiman.rshu.ru) 3 Finnish Meteorological Institute, Finland, (pertti.nurmi@fmi.fi)

2. NOWCASTING SYSTEMS FOR SOCHI 2014 WINTER OLYMPICS RDP Model–based Pointwise 10 min/6 hours Temperature Humidity Wind direction and speed Precipitation INTW (Env.Canada) FDP Radar –based Pointwise 10 min/1,5 hour Only precipitation (rate and accumulated) CARDS (Env.Canada) FDP Blended (Radar +NWP) Gridded (1km) 10 min/ up to 48 hours Temperature Humidity Wind direction, speed and gusts Precipitation (10 min) INCA (ZAMG, Austria) FDP Radar –based Pointwise 10 min/4 hours Temperature Humidity Wind direction, and speed Precipitation Visibility Ceiling MeteoExpert ( IRAM, Russia) FDP Model–based Pointwise Hourly/up to 48 hours Temperature, Humidity Wind speed, direction and gusts MSLP Joint (Multi-system forecast integration, RHM)

3. QUICK LOOK AT THE DATA Nowcasting (precipitation accumulation): CARDS – (10 min) from 25.01.2014 till 31.03.2014 INCA - (10 min) from 27.01.2014 till 19.03.2014 INTW – (10min) from 18.02.2014 till 03.04.2014 Stations used in verification: Imeretinka (37095), 6m, precip: Vaisala VRG101 Ski Jump (39040), 630m, precip: OTT Pluvio-2 Biathlon Stadium (39044), 1460 m, precip: OTT Rosa Khutor 3, 2043 m, precip: ARG100 Verification aspects: Point-wise forecast vs. observation Categorical verification Subjective evaluation by forecasters CARDS Visualization INTW Visualization

4. NOWCASTS Evaluated Subjectively 4 ‐ point scale: 0 – not useful 1 – partly useful 2 – useful 3 ‐ excellent Overall forecasters’ opinion was that the available technologies were very helpful Except: Perhaps too many systems (difficult to absorb in operational setting)

5. CARDS (25.01. - 31.03.2014) Some extremes observed but not forecasted - 29.03 and 31.03 Some good forecasts: - 02.02 -18.02, no precipitation -16.03, fcst and obs 3-4mm/h (but not for Imeretinka) Some false alarms - 02.03 - 09.03

6. Point forecasts statistics for CARDS

7. INCA (27.01. – 19.03.2014) Some extremes observed but not forecasted 29.01 and 17.03 Some good forecasts: - 02.02 -16.02, no precipitation -12.03 and 16.03, fcst and obs 2-4mm/h (not for RKHU 3)!

8. Point forecasts statistics for INCA

9. INTW (18.02. – 03.04.2014) Some events observed but not forecasted - 21.02 and 31.03 Some good forecasts: - 21.02 -26.02, no precipitation - 05.03 and 27.03, fcst and obs 2mm/h (not for RKHU 3)! Some false alarms - 16-18.03 and 20.03

10. Point forecasts statistics for INTW

11. Skill (HSS) for 3 Nowcast Systems : CARDS, INCA, INTW 1.In general, all nowcasts demonstrate relatively good skill. 2.They were considered very useful by forecasters during the Games. 3.CARDS shows best overall scores. 4.Underestimation at some sites but, contradictory: Poor forecasts of intense precipitation (missed events).

12. LESSONS LEARNED Nowcast problems (all models) : Timing: Time of the start and end of phenomena (precipitation) Precipitation amount in case of weakly developed processes Maximum wind speed Visibility and ceiling Forecasters’ model-related challenges: Number of products is both an advantage and a challenge – with many new products and time for decision-making is strictly limited Degree of model usage depends on the degree of forecasters’ familiarity with models and, therefore, confidence in it (more familiar = more usable) Forecasters (other end-users as well) need time to adapt to new products Forecasting issues during the Olympics Key role of forecasters in: Integration and control of diverse and (sometimes) contradictory model information Decision-making process for the high-impact events !